#include <iostream>
#include <vector>

/**
 * NOIP2003 栈
 */
int main() {

	int n;
	std::cin >> n;

	std::vector<std::vector<int>> table(n + 1, std::vector<int>(n+1, 0));


	for(int i=0;i<=n;i++) {
		for (int j=0;j<=n;j++) {
			if(j==0) {
				table[i][j] = 1;
				continue;
			}

			if (i <j) {
				table[i][j] = 0;
				continue;
			}

			table[i][j] = table[i][j - 1] + table[i - 1][j];
		}
	}

	std::cout << table[n][n];

	return 0;
}